doyle DISPATCH — #307 W1a: #308 (serve-registry lost-update). Operator directive: #307 greenlit, drive to v0.71.0. Full plan: .spt/preserved/307/JIT-PLAN.md (also commented on #307).

Your prep draft fix/308-registry-process-lock @fefc4d64 (base 7890ead3) is the starting point. Do:
1. Rebase onto main 289e3cdf in .worktrees/308-registry-process-lock; pool-claim from that worktree.
2. Build; run the new fail-closed unit + the two-process int (serving_registry_two_process_int.rs, worker fixture) via nextest; targeted serving + webserve_attachment_e2e suites. Make the int red on purpose first (drop the OS lock) so the cell is proven live.
3. Activate the REQ stages in traceable-reqs.toml in the SAME commit as the evidence; traceable-reqs 0.4.1 check exit 0.
4. Thin PR off 289e3cdf, co-author trailer space spelling. Report head sha + PR + the red-first receipt. I gate in an isolated worktree.
Box: hfenduleam runner idle; hertz runs two light isolated-home rigs in parallel (CPU contention only). 182 GB free — do not leave a retired target behind.
Then W2a (#309) queues behind this on your lane; do not start it until #308 is handed to gate.